1. Technical Field
The present invention relates to a printing apparatus which performs a printing operation by ejecting a liquid such as an ink or a recording liquid from a printing head onto a recording medium supported by a supporting member and a method for adjusting a gap.
2. Related Art
JP-A-2011-67964 (FIG. 1) discloses a printing apparatus in which a plurality of printing heads eject liquids such as different inks or recording liquids onto a recording medium such as a film so as to record a color image. In the printing apparatus, the recording medium is wrapped around a cylindrical platen drum in a state of tension being applied to the recording medium and is supported on a curved cylindrical surface. The plural printing heads are disposed around the platen drum so as to surround the platen drum.
In order to perform high quality printing, it is necessary to position the respective printing heads at predetermined orientations with respect to the platen drum. In particular, if any printing head comes to be in a slanted state, that is, a so-called “tilted state” with respect to the platen drum, a nozzle mounted on a distal end of the printing head in question comes to be in a non-parallel orientation relative to the surface of the platen drum, and a landing position of the liquid ejected from the nozzle onto the recording medium is deviated from a desired position. Accordingly, heretofore, the slanted state of the printing head was adjusted by mounting an adjusting mechanism on a carriage that holds and moves the printing head so as to adjust the slanted orientation, that is, a tilted angle, or by adjusting an angle of the carriage itself to make the nozzle parallel to the surface of the platen drum.
However, this adjusting mechanism is relatively large and requires a space in which to be installed. Consequently, the adjusting mechanism results in an increase in size of the carriage. Since the adjusting mechanism adopts a so-called trial and error method in which the mechanism performs operations to adjust and confirms the tilted state of the printing head repeatedly, there is a problem that much time and manpower are required for adjustment. In addition, since the printing apparatus disclosed in JP-A-2011-67964 is provided with a plurality of printing heads, it is necessary to perform adjustment of the tilted state for every color. This makes adjusting works complicated and results in an increase in the size of the apparatus.